This invention is more than, arid thereby different from, instruments which individually either compress or expand the spinial bones, for instance. The prior art cited in this instance discloses instruments or tools which individually can manipulate bones, such as by extension or compression thereof.
The present invention improves upon the known instruments in that it provides an instrument for compression and distraction of bones, and it does so with an instrument which is arranged with a mechanical advantage of a nature which produces universal, that is, complete, variations in the instruments working jaws which are in contact with the bones. More specifically, there is no incremental, or step-by-step positioning of the jaws, but, instead, the jaws are smoothly and infinitely positionied in maneuvering of the jaws.
Accordingly, it is an object of this invention to provide a compression and distraction instrument for use in the medical field and to have the instrument operative under a mechanical advantage and in a smooth and continuous operation whereby the working jaws are smoothly and uniformly positioned for compression and distraction.
Accordingly, the instrument of this invention accomplishes the aforementioned and it does so by means of jaw surfaces which remain parallel to each other in both the compression and distraction function and while the jaws are moved toward and away from each other in a uniform or smooth movement.
A screw connects to two pivotal handles, and there is an anti-friction connection therebetween. One embodiment has the screw disposed longitudinally of the instrument, and the other embodiment has the screw pivoted to the handle for connection,